 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.console;

 import org.eclipse.core.expressions.EvaluationContext;
 import org.eclipse.core.expressions.EvaluationResult;
 import org.eclipse.core.expressions.Expression;
 import org.eclipse.core.expressions.ExpressionConverter;
 import org.eclipse.core.expressions.ExpressionTagNames;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.ui.IPluginContribution;
 import org.eclipse.ui.console.IConsole;
 import org.eclipse.ui.console.IConsolePageParticipant;

 public class ConsolePageParticipantExtension implements IPluginContribution {

     private IConfigurationElement fConfig;
     private Expression fEnablementExpression;

     public ConsolePageParticipantExtension(IConfigurationElement config) {
         fConfig = config;
     }

     /* (non-Javadoc)
      * @see org.eclipse.ui.IPluginContribution#getLocalId()
      */
     public String getLocalId() {
         return fConfig.getAttribute("id"); //$NON-NLS-1$
 }

     /* (non-Javadoc)
      * @see org.eclipse.ui.IPluginContribution#getPluginId()
      */
     public String getPluginId() {
         return fConfig.getContributor().getName();
     }
     
     public boolean isEnabledFor(IConsole console) throws CoreException {
         EvaluationContext context = new EvaluationContext(null, console);
         EvaluationResult evaluationResult = getEnablementExpression().evaluate(context);
         return evaluationResult == EvaluationResult.TRUE;
     }
     
     public Expression getEnablementExpression() throws CoreException {
         if (fEnablementExpression == null) {
             IConfigurationElement[] elements = fConfig.getChildren(ExpressionTagNames.ENABLEMENT);
             IConfigurationElement enablement = elements.length > 0 ? elements[0] : null;

             if (enablement != null) {
                 fEnablementExpression = ExpressionConverter.getDefault().perform(enablement);
             }
         }
         return fEnablementExpression;
     }

     public IConsolePageParticipant createDelegate() throws CoreException {
         return (IConsolePageParticipant) fConfig.createExecutableExtension("class"); //$NON-NLS-1$;
 }

 }

